A Pilgrimage to Ottawa

[ChasingGhostsYT]

Howdy again!

 

   Following my trip to Kingston a few days prior to this post, I decided to scout some sites elsewhere. It just so happened the family trip took us to Ottawa today to see the Science and Tech Center, as well as the Nature museum. 
   Being a bit opportunistic, I convinced the rest to take a detour to the southern bank of the Ottawa River to test my luck at scouting a new site. I’ve been reading posts across the form about Ottawa’s Billings Shale, and wanted to try my hand at finding some triarthrus and Pseudogygits. 
   As I arrived I realized something was off; the dark pyritic shale I was anticipating turned out to be a rather course dolostone. I had instead found myself in the Oxford Formation, and with little time to check out sites I marked nearby, I decided to make the best of it.

   With the 20 minutes I had to scan the bank for suitable rocks to break down, I found a pretty cool run of Crinoid, and as I flipped the rock over I discovered a small enrolled trilobite! It looks like the pluerea continue, so I’m hopeful I’m coming home with at least one complete!! 
   Now I turn to the form here to help me ID this bug. I had done little research on the Oxford formation, as it’s not where I intended to end up, so I know little about the bugs here. Looks to me like some form of Calymene, but I’m unsure.
 

Trilobite in Question:

 

 

 

Host Rock (Trilobite Side)

 

: 

 

Host rock, Crinoid side:

 

 

[FossilDAWG]

I'm skeptical that you were actually collecting in the Oxford.  The Oxford is a very pure brownish dolomite, without shale partings or other clastic components.  Fossils are rare but they do occur here and there.  However they are overwhelmingly gastropods, especially Ceratopea and indeterminate high-spired forms resembling Hormotoma, and most of them are highly silicified.  Trilobites are very very rare, just a couple of Lower Ordovician forms, and no articulated (whole) trilobites are known.  No calymenids have ever been reported.  Trilobites are so rare that every fragment is scientifically important.  In addition crinoid material is absent, and even articulated crinoid stems have not been found.  I strongly suspect you have a piece from the Pamelia or some higher horizon within the Ottawa Group.  The Pamelia and Rockland have layers of somewhat dolomitic limestone, as well as purer limestone, with shale partings, abundant trace fossils, and crinoid stems, trilobites, brachiopods, bryozoans, etc.  Along the river banks you can get a real mix of things, as rock has been moved all around for fill, construction, glacial erratics etc.  It's hard to assign a loose piece to a specific horizon.  If it was collected in situ from a bedrock exposure you can have more confidence.  BTW I lived in Ottawa for several years so I'm familiar with the challenge of deciphering the geology.

 

Don

[ChasingGhostsYT]

34 minutes ago, FossilDAWG said:

I'm skeptical that you were actually collecting in the Oxford.  The Oxford is a very pure brownish dolomite, without shale partings or other clastic components.  Fossils are rare but they do occur here and there.  However they are overwhelmingly gastropods, especially Ceratopea and indeterminate high-spired forms resembling Hormotoma, and most of them are highly silicified.  Trilobites are very very rare, just a couple of Lower Ordovician forms, and no articulated (whole) trilobites are known.  No calymenids have ever been reported.  Trilobites are so rare that every fragment is scientifically important.  In addition crinoid material is absent, and even articulated crinoid stems have not been found.  I strongly suspect you have a piece from the Pamelia or some higher horizon within the Ottawa Group.  The Pamelia and Rockland have layers of somewhat dolomitic limestone, as well as purer limestone, with shale partings, abundant trace fossils, and crinoid stems, trilobites, brachiopods, bryozoans, etc.  Along the river banks you can get a real mix of things, as rock has been moved all around for fill, construction, glacial erratics etc.  It's hard to assign a loose piece to a specific horizon.  If it was collected in situ from a bedrock exposure you can have more confidence.  BTW I lived in Ottawa for several years so I'm familiar with the challenge of deciphering the geology.

 

Don

  Thanks for the information man!

 

  I have become aware of the almost impossibility that the trilobite I have is from the Oxford Fm. Adding to the crinoid stem on the back I’m leaning further towards the possibility of this rock coming from quarried fill. 
   As for the matter of situ I’ve confirmed where I was collecting was 100% the Oxford Fm, and I broke this chunk from a larger rock (most of which contained that brownish almost rustish rock you describe) along the shoreline…. I interpreted this larger rock as bedrock…however plenty of rock around the shoreline was limestone fill. 
  Im skeptical myself of this rock being from Oxford, it was brought to my attention that the crinoid stem found on the backside is commonly found within the Bobcaygeon Fm, which is heavily quarried into for Ottawa’s fill. 
  When I get home I’m gonna arrange for this bug to be prepped so we can confirm either side of this coin.

  I appreciate the hell out of the local info man! I’ve been busting to try to have some successful digs up here, and I plan to be back into the Ottawa area tomorrow to see if I can actually hit the Billings this time around.

 

[Kane]

A significant amount of the Billings shale was excavated to put in the O-Train downtown leg (route 1). I have no idea where they may have transported it, but I know when I was a kid living there back in the 80s, there was a municipal shale dump somewhere in Orleans when Orleans was mostly a few small neighbourhoods and farmland.

[ChasingGhostsYT]

14 minutes ago, Kane said:

A significant amount of the Billings shale was excavated to put in the O-Train downtown leg (route 1). I have no idea where they may have transported it, but I know when I was a kid living there back in the 80s, there was a municipal shale dump somewhere in Orleans when Orleans was mostly a few small neighbourhoods and farmland.

Thank you for the information man!

   I’ll have to take some time scanning google maps for shale dumps… if up here is anything like down in the US I’d imagine that dump from the 80s has long since been picked through😂 I do greatly appreciate being pointed in the right direction though! 
   I guess the only question I’d ask right now, and bare in mind I ask it very generally to protect the integrity of sites, but using some geo maps I found a stretch along The Rideau that is mapped as Billings. If I walk the bank and rockhound along the shore as I did with the Ottawa River, what are my chances of actually reaching bedrock? I would need to refrain from any digging as I’d prefer not to kick up sediment or disturb much of the bank. Will I show up and find fill dumped over the bank, or will the bank be compromised of the Billings shale?

 

 

[FossilDAWG]

The problem is that there are essentially no natural exposures of the Billings, or the overlying Carlsbad Shale and Russel Formation.  The Carlsbad is quite fossiliferous, equivalent to the Georgian Bay Formation in southern Ontario and also the Lorraine in Quebec.  For all these formations you have to find construction sites that dig in to them, then figure out where the excavated rock is being dumped.  There used to be shale dumps south of town along Bank Street but they were gone last year when I visited.  The rock is often used for fill so the dumps are just temporary.  You basically have to get lucky.  I only ever got to collect the Carlsbad once but I have drawers of fossils including quite a few complete trilobites.  The dump site only lasted one summer before it was hauled away.  So drive around the outskirts and look for piles of black or grey rock, or maybe follow dump trucks leaving fresh construction sites.  Or cultivate contacts in the local collector community if you can.